Lecture 2: Climate Flashcards
What causes the daily periodicity on Earth (day vs. night)?
the rotation of the Earth around its axis
What causes the lunar cycles (tides)?
The revolution of the moon around the Earth
How long are the lunar cycles?
~27 days
What causes seasonal patterns by hemisphere?
the revolution of the Earth around the sun combined with the tilted axis of the earth
What is the degree of the Earth’s tilted axis?
23.5 degrees
Define climate
the long term average patterns of temperature, humidity, precipitation, wind, atmosphere pressure, etc.
What scales can climate be described at?
local, regional or global
Define weather
A combination of temperature, humidity, precipitation, wind, atmospheric pressure, etc. in a particular time or place
What are the 4 major components of climate?
- electromagnetic radiation (light and temperature)
- winds
- ocean currents
- precipitation
Approximately how much of the incoming solar radiation reaches the Earth’s surface?
~ 51%
If 100% of solar radiation are incoming to Earth, what % of SR is absorbed by clouds and the atmosphere?
~19%
If 100% of solar radiation are incoming to Earth, what % is reflected back to space by clouds and the atmosphere?
~30%
Of the ~51% SR that that reaches the earth’s surface, what % heats land and oceans?
What happens to the remaining % of SR?
~21%
the remaining ~30% is either used up in evaporation or thermal energy
Of the ~51% SR that that reaches the earth’s surface, what % evaporates water off the surface of the Earth?
~23%
Of the ~51% SR that that reaches the earth’s surface, what % is used up to heat air next to the surface (aka thermals)
~7%
What % of SR is radiated by the Earth’s surface?
117%
What is the name of the effect/process that re-radiates the SR radiated by the Earth’s surface back to the Earth in order to maintain a hospitable temperature?
What % SR does it trap and what % does it re-radiate back to Earth?
The Greenhouse Effect
traps 111%
re-radiates 96%
What % SR is lost to space after it has been radiated from the Earth?
~6%
What type of SR is radiated back to Earth as a result of the Greenhouse Effect?
Thermal radiation (longwave)
What type of radiation is directly from the sun?
Solar radiation (shortwave)
What are the overall inputs of SR for Earth?
51 units from sun reaches Earth + 96 units radiated back from GHE = 147 units
All inputs are SR/shortwave
What are the overall outputs of SR for Earth?
30 units SR to space + 117 to atmosphere = 147 units
All outputs are thermal radiation/longwave
Does the approximate amount of SR that reaches the Earth’s surface balance the amount that leaves?
Yes, about 147 units gained and lost
Describe the Greenhouse Effect
When SR reaches the surface, the radiation is converted into lower-energy infrared radiation which is radiated from earth and absorbed by the GHG in the atmosphere (ex. water vapour, CO2, methane).
This lower energy radiation is re-radiated back to Earth
What is the significance of the Greenhouse Effect?
The earth loses so much thermal radiation (~117%) so the GHE traps and re-radiates most of it back to the Earth in order to maintain a temperature that is conducive to life
T or F: most of the heat radiated by the Earth is radiated back by the atmosphere?
True
What are the two kinds of electromagnetic radiation?
- solar radiation
2. thermal radiation
What are the wavelengths and types of solar radiation?
Ultraviolet light, visible light, and near infrared light
Wavelengths: 100nm-5000nm
What wavelength range is visible light in?
400nm-700nm
Describe visible light
Solar radiation that is within the visible range for humans and the region that plants use for photosynthesis
What does PAR stand for?
Photosynthetically Active Region
Describe UV radiation?
Solar radiation that is harmful and can cause mutations
Bees and other pollinators can see UV radiation but humans cannot
What are the wavelengths and types of thermal radiation?
far infrared
wavelengths: 5000-100,000nm
Describe thermal radiation
the long-wave radiation off the surface of the earth that is also radiated back from the atmosphere as part of the GH effect
Give an example of how animals can use thermal radiation to their advantage
Pit vipers can sense thermal radiation to sense the heat signatures of their prey
Define albedo
the fraction of solar radiation reflected by an object
it also depends on the properties of the surface
Describe the albedo effect on dark-coloured surfaces
Dark colours absorb more SR and heat up
Describe the albedo effect on light-coloured surfaces
Light colours reflect more SR and remain cooler in temperature
T or F: albedo effect has little impact on climate
FALSE. It has a major impact on climate
If a surface has low albedo it is…
darker in colour because the fraction of light it will reflect is low
If a surface has high albedo it is…
lighter in colour because the fraction of light it will reflect is high
What albedo level does fresh snow have?
HIGH - 80-90%
What albedo level does sea ice have?
HIGH - 50-90%
What albedo level does water have?
10-60%